Robotic surgery planar cutting systems and methods

ABSTRACT

Examples of robotically controlled planar cutting systems and methods for controlling cutting systems to prepare bone tissue in surgical procedures, are generally described herein. Applicable surgical procedures for the robotically controlled cutting systems and methods include procedures involving the preparation (e.g., removal, surfacing) of bone tissue, such as is performed in knee arthroplasties. 
     In an example, a robotically controlled planar cutting system can include a housing, a cutting element disposed in the housing, and a cutting control mechanism in communication with a robotic controller to control operation of the cutting element to machine a planar surface. The cutting element can be exposed and retracted relative to the housing and can include a plurality of cutting implements arranged to machine the planar surface.

RELATED APPLICATION

The present application is a continuation of U.S. Non-Provisionalapplication Ser. No. 16/265,318 filed on Feb. 1, 2019 which claimspriority on U.S. Provisional Application Ser. No. 62/625,556, filed onFeb. 2, 2018, and incorporated herewith by reference.

TECHNICAL FIELD

This disclosure is generally related to tools and methods for removingbone during a surgical procedure. In particular, the tools and methodsdescribed herein can be used to prepare a bone surface during a totalknee arthroplasty.

BACKGROUND

The use of robotics in surgery is on the rise. Knee arthroplastysurgeries are performed over half a million times a year in the UnitedStates. In some cases, the surgeries are performed with assistance froma surgical robot.

Surgical robots can be outfitted with cutting tools for preparing a bonesurface. In some surgeries, bone tissue must be prepared to receive animplant having a specified geometry. Preparing the bone tissue caninclude removing a portion of the bone tissue in order to modify thebone surface shape and make room for the implant.

SUMMARY

Therefore, in accordance with the present disclosure, there is provideda robotically controlled planar cutting system, the planar cuttingsystem comprising: a housing including a superior surface and aninferior surface; a cutting element disposed within the housing, whereinthe cutting element is exposable through the superior surface and ispopulated with at least one cutting implement configured for machining aplanar surface; and a cutting control mechanism configured for being incommunication with a robotic controller to control the operation of thecutting element to machine the planar surface.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 illustrates a surgical robot having a cutting system coupled toan end effector, in accordance with at least one example.

FIG. 2 illustrates a perspective view of an example cutting system thatcan be used with the surgical robot of FIG. 1 , in accordance with atleast one example.

FIG. 3 illustrates a plan view schematic showing an example geometry ofthe cutting system of FIG. 2 , in accordance with at least one example.

FIG. 4 illustrates a plan view schematic of another example geometry ofthe cutting system of FIG. 2 , in accordance with at least one example.

FIG. 5 illustrates a plan view schematic of another example geometry ofthe cutting system of FIG. 2 , in accordance with at least one example.

FIG. 6 illustrates a system for performing a surgical procedureincluding tracking and control, in accordance with at least one example.

FIG. 7 illustrates a flowchart showing a technique for performing asurgical procedure using a cutting system attached to an end effector ofa surgical robot, in accordance with at least one example.

FIG. 8 illustrates a flow chart showing a technique for surgicaltracking and control, in accordance with at least one example.

FIG. 9A illustrates a perspective view of another example cutting systemhaving cutting implements that can be used with the surgical robot ofFIG. 1 , in accordance with at least one example.

FIG. 9B illustrates a perspective view of the cutting system of FIG. 9Awith a housing removed, in accordance with at least one example.

FIG. 10 illustrates a perspective view of a portion of the cuttingsystem of FIG. 9A showing another example of cutting implements, inaccordance with at least one example.

FIG. 11 illustrates a perspective view of examples of cutting implementsthat can be used in the cutting system of FIG. 10 , in accordance withat least one example.

FIG. 12 illustrates a schematic sectional view of examples relativemovements of cutting system relative to rotational axes and to ahousing.

DETAILED DESCRIPTION

As discussed above, surgical robots can be outfitted with cutting toolsfor preparing a bone surface. In some surgeries, bone tissue is preparedto receive an implant having a specified geometry. Preparing the bonetissue can include removing a portion of the bone tissue in order tomodify the bone surface shape.

During a knee arthroplasty, e.g., a total knee arthroplasty, it can bedifficult to prepare (e.g., cut) a planar bone surface to receive animplant. Current surgical robots and cutting systems are limited intheir ability to machine a planar bone surface to match the implantsurface to be received. Moreover, it is often desired that surgery be asminimally invasive as possible. Yet, cutting planar bone may ofteninvolve lateal and axial access to the bone, which may involve relativelarge incisions in soft tissue.

Systems and methods for preparing a bone surface during an orthopedicknee procedure and for performing the procedure are described herein.The systems and methods can assist in planar surface preparation, andmay reduce surgical time.

While some examples are described with reference to total kneearthroplasty, many of the techniques described herein can be used withother orthopedic implant procedures.

FIG. 1 illustrates a surgical robot 10 having a cutting system 100coupled to an end effector 20, in accordance with at least one example.The surgical robot 10 can be a robotic arm 30, and can include a userinterface 40, a robotic controller 50, and a tracking system 60 operablycoupled to one another. In some examples, the robotic arm 30, the userinterface 40, the robotic controller 50 and the tracking system 60 canbe coupled to a base 70.

The cutting system 100 can include an end effector 20 connectionmechanism 116 adapted to couple the cutting system 100 to an endeffector 20 of the robotic arm 30.

To enable a cutting operation to be performed, the cutting system 100can include a cutting element 104 disposed in a housing 106. The cuttingelement 104 can be populated with a plurality of cutting implements 108that are arranged to machine a planar surface. Examples of a cuttingelement 104 having a plurality of cutting implements 108 will bedescribed in FIGS. 2-5 and 9-11 . Together, the plurality of cuttingimplements 108 can form a two-dimensional cutting surface capable ofmachining a planar bone surface (to receive an implant).

An actuator 102 may be present to move the cutting element 104 disposedin the housing 106, relative to the housing 106 to extend or retract thecutting element 104. In an embodiment, the cutting element 104 may movein a planar direction while the housing 106 is fixed relative to thebone.

In some examples, the entire cutting element 104 can be extended orretracted with respect to the housing 106 by the actuator 102 such thatthe two-dimensional cutting surface can be selectively exposed outsidethe housing 106. In other words, the actuator 102 can, but is notrequired, to move the plurality of cutting implements 108 together. Insome examples, the actuator 102 can move at least one of a plurality ofcutting implements 108 relative to a housing 106 to extend or retractthe at least one of the plurality of cutting implements 108, and/or movethe cutting implements in a plane relative to the housing 106, i.e., ina plane to which a direction of extension/retraction is normal.

The cutting system 100 can also include an oscillator 110 to oscillatethe cutting element 104. In some examples, the oscillator 110 canoscillate only some of the plurality of cutting implements 108. Theoscillator 110 can also oscillate each of the plurality of cuttingimplements 108 relative to the housing 106, or the plurality of cuttingimplements 108 can be oscillated together relative to the housing 106.In some examples, the housing 106 can be oscillated together with thecutting element 104.

The cutting system 100 can also include a rotator 112 to rotate thehousing 106 and the cutting element 104. In some examples, the rotator112 can rotate the cutting element 104 (including the plurality ofcutting elements 108 together) relative to the housing 106. The rotationaction provided by the rotator 112 can be described as providing asecond motion component, in addition to any first motion component thatis provided to each of the plurality of cutting implements 108.

The cutting system 100 can be controlled by a control system including acutting control mechanism 114 that is in communication with the roboticcontroller 50 of the surgical robot 10. The control system 610 isdescribed in further detail in FIG. 6 .

FIG. 2 illustrates a perspective view of a portion of an example cuttingsystem 200 that can be used in conjunction with the surgical robot 10 ofFIG. 1 . In general, the cutting system 200 can be used to prepare aplanar bone surface.

A housing 206 can include a superior surface 218 at a distal end portionand an inferior surface 220 opposite the superior surface 218. Aperimeter 222 of the distal end portion of the housing 206 can include ashield 224 around a cutting element 204 (e.g., a plurality of cuttingimplements 208). The shield 224 can protect soft tissue located adjacentto a bone cutting site from inadvertent contact with the plurality ofcutting implements 208. The shield 224 may have a contour design orfabricated to be patient specific, for example in the form of a lip. Thepatient specific shield 224 may be fabricated using pre-operativeimaging of the bone, in such a way to be a negative of the bone surface,for the complementary abutment between the shield 224 and the surface ofthe bone.

In the example of FIG. 2 , the housing 206 is shown having a generallytrapezoidal perimeter 222 around the plurality of cutting implements208. The generally trapezoidal perimeter 222 can be shaped to complementthe shape of a cross-sectional a bone surfaces to be machined (e.g.,femur, tibia). Other perimeter shapes can be provided, includinggenerally triangular, parallelogram, rectangular or irregular shapes.The plurality of cutting implements 208 can be disposed within thehousing 206 and can be exposable through the superior surface 218.

The cutting element 204 can be populated with the plurality of cuttingimplements 208 that are arranged to machine a planar surface. Together,the plurality of cutting implements 208 can form a two-dimensionalcutting surface. In some examples, the entire cutting element 204 can beextended or retracted with respect to the housing 206 such that thetwo-dimensional cutting surface can be exposed outside the housing 206.

The cutting control mechanism 114 (FIG. 1 ) can be in communication withthe robotic controller 50 (FIG. 1 ) to control operation of the cuttingelement 204. The cutting control mechanism 114 (FIG. 1 ) can control theoperation of each of the plurality of implements 208 together, orseparately.

The cutting control mechanism 114 (FIG. 1 ) can receive signals from therobotic controller 50 (FIG. 1 ) to expose or retract the cutting element204, and therefore the two-dimensional cutting surface, outside of thehousing 206. The cutting control mechanism 114 (FIG. 1 ) can alsoactivate or deactivate the entire cutting element 204, or the individualplurality of cutting implements 208 individually, based on signals fromthe robotic controller 50 (FIG. 1 ). The activation and/or deactivationof all or some of the cutting implements 208 (or all other cuttingimplements described herein), along with other control features such asthe deceleration of the cutting implements 208, may be performed toavoid removing bone that it is desired to preserve. Stated differently,some selective disabling of cutting implements may be controlled toavoid certain bone, such as bone in a no-cut zone.

As shown in the example of FIG. 2 , the plurality of cutting implements208 can include a plurality of cutting mills 216 disposed in a pattern(e.g., array). To perform a milling operation, each of the plurality ofcutting mills 216 can be rotated respectively upon activation of thecutting element 204, about axes R. In an embodiment, all axes R areparallel to one another, and normal to a resulting two-dimensionalcutting surface (a.k.a., cutting plane) on the bone. The rotationalmotion of each of the plurality of cutting mills 216 can be described asa first motion component delivered to the cutting element 204. Inanother example, instead of the first motion component being rotational,each cutting mill 216 of the plurality of cutting mills 216 canoscillate upon activation of the cutting element 204 (e.g., each of theplurality of cutting mills may not fully rotate, but rather canoscillate about axes R).

The plurality of cutting mills 216 be arranged and controlled tocooperate with each other such that together the plurality of cuttingmills 216 are capable of machining a planar bone surface.

To facilitate cutting a planar bone surface with the plurality ofcutting mills 216, the cutting system 200 can include a structure tooscillate or rotate the cutting element 204. The cutting element 204 canbe oscillated or rotated together as a whole. The oscillation orrotation of the cutting element 204 (e.g., as a whole) can be inaddition to rotational or oscillating movement provided to each of theplurality of cutting mills 216. By oscillating or rotating the cuttingelement 204 as a whole, the plurality of cutting mills 216 can machinethe bone tissue located in between the plurality of cutting mills 216during a surgical procedure. This oscillating or rotating movement ofthe cutting element 204 as a whole can enable the cutting system 200 toform a two-dimensional cutting surface. The two-dimensional cuttingsurface can thus be capable of milling a planar bone surface. Thecutting element 204 can also be translated along the bone surface tocreate the planar bone surface, namely move along axis X and/or axis Y.

FIG. 3 illustrates a plan view schematic showing an example geometry 300of the cutting system 200 of FIG. 2 . In the example shown, a pluralityof cutting mills 316 can include five cutting mills 316 positioned in atrapezoidal arrangement. A trapezoidal arrangement can be described asoccurring when lines 326 tangent to outer radii of the cutting mills 316generally form a trapezoid. A trapezoidal arrangement can also bedescribed as occurring when lines from center to center of the cuttingmills 316 (i.e., at axes R) form a trapezoid.

In some examples, the plurality of cutting implements can be some numberother than the five cutting mills 316 shown in FIG. 3 . For example,three cutting mills positioned in a triangular arrangement may beprovided. A triangular arrangement can be described similarly to thetrapezoidal arrangement (e.g., lines tangent to outer radii of thecutting mills form a triangle). A single cutting mill may also bepresent, and may move along axis X and/or axis Y.

In some examples, the plurality of cutting mills include four cuttingmills positioned in a generally parallelogram arrangement or in arectangular arrangement. In other words, a parallelogram arrangement canbe described as lines tangent to outer radii of the cutting mills form aparallelogram. A rectangular or parallelogram arrangement can also bedescribed as occurring when lines from center to center of the cuttingmills 316 (i.e., at axes R) form a rectangle or a parallelogram.

Another way of describing the location of the plurality of cutting mills216 relative to each other is shown in the examples of FIGS. 3-5 . Theplurality of cutting mills 316 (FIG. 3 ), 416 (FIG. 4 ), 516 (FIG. 5 )can include a first cutting mill 1, a second cutting mill 2, a thirdcutting mill 3, a fourth cutting mill 4 and a fifth cutting mill 5.

As shown in FIGS. 3-5 , the first, third and fifth cutting mills 1, 3, 5can be located adjacent to one another, and the second and fourthcutting mills 2 may be staggered with respect to the first, third andfifth cutting mills 1, 3, 5. This arrangement of the implements may bedescribed as a staggered or zig-zag type arrangement.

As shown in the geometry of FIG. 3 , in some examples, an axis 328extending tangent from the first cutting mill 1 to the third cuttingmill 3 can be tangential to the second cutting mill 2. Likewise, theaxis 328 can also extend tangent from the third cutting mill 3 to thefifth cutting mill 5 and can be tangential to the fourth cutting mill 4.

As shown in the geometry of FIG. 4 , in some examples, an axis 428extending tangent from the first cutting mill 1 to the third cuttingmill 3 can intersect the second cutting mill 2. Likewise, the axis 428can also extend tangent from the third cutting mill 3 to the fifthcutting mill 5 and can intersect the fourth cutting mill 4.

As shown in the geometry of FIG. 5 , in some examples, the axis 528extending tangent from the first cutting mill 1 to the third and fifthcutting mills 3, 5 may not necessarily intersect the second or fourthcutting mills 2, 4. Instead, the first third and fifth mills 3, 5 can bespaced apart from the second and fourth mills 2, 4. As shown in FIG. 5 ,the first, third and fifth cutting mills 1, 3, 5 can be located belowthe axis 528, and the second and fourth cutting mills 2, 4 can belocated above the axis 528.

The various cutting implements described above, such as 108, 216, 316,416 and 518 may be driven in any appropriate way. As shown in FIG. 12 ,it may be desired to move these cutting implements in a X,Y plane towhich rotational axes R are normal, or along directions X or Y. Thecutting implements may have their own motors, or may have atransmission. The transmission may include an endless worm and gears,tendons and pulleys, chains and sprocket. For example, the actuator 102may include a shaft 102A that is oriented transversely relative to therotational axes R, and connected thereto by a transmission A. This mayallow the maneuvering of the cutting systems 100 and 200 from a lateralapproach, as opposed to displacing the cutting systems 100 and 200 alonga direction parallel to axes R. To assist in keeping the cutting system100 and 200 fixed relative to the bone, clamps or temporary fasteners Bmay be used.

FIG. 6 illustrates a system 600 for performing a surgical procedureincluding tracking and control in accordance with some embodiments. Thesystem 600 will be described with respect to the surgical robot 10 andcutting system 100 shown in FIG. 1 , but the system 600 can also be usedwith other surgical robots and cutting systems.

The system 600 can include a robotic arm 30 including an end effector20, a tracking system 60, and a control system 50. The system 600 canalso include a cutting system 100 having a cutting element 104. Therobotic arm 30 can be configured to allow interactive movement andcontrolled autonomous movement of the end effector 20. The system 600can be configured to control the cutting element 104 to machine a planarsurface.

The tracking system 60 can include a camera 62 or an infrared sensor 64.The tracking system 60 can use the camera 62 or the infrared sensor 64to track the robotic arm 30, the end effector 20, the cutting element104, a target object, or the like. In an example, the tracking system 60can be used to determine a position and/or an orientation of the cuttingelement 104. The position or the orientation can be determined relativeto a coordinate system or relative to a target object. In an embodiment,the bones and end effector 20 are in a common three-axis coordinatesystem. An example optical tracking device commonly used for this typeof application is the Polaris Optical Tracking System from NorthernDigital of Waterloo, Ontario, Canada. The camera 62 may for example be athree-dimensional (3D) camera having two points of view to providepositional readings for objects in a 3D coordinate system. For example,the camera 62 may track retro-reflective trackers, such as shown at 60′in FIG. 1 . While only one such tracker 60′ is shown in FIG. 1 , thetracking system 60 may have additional trackers 60′, such as one on therobotic arm 30 (e.g., in proximity to the end effector 20 or on the endeffector 20 or cutting system 100), and/or one or more on the bone(s)underdoing resurfacing surgery. In an embodiment, a tracker has three ormore reflective elements, arranged in a unique geometry. The trackingsystem 60 may further be programmed with geometrical data to correlatethe trackers 60′ with the objects they are on. Using the geometricaldata, the tracking system 60 can determine a position and/or orientationof the cutting elements 108 relative to the coordinate system andrelative to the bone. This tracking system 60 may further includeencoders in the joints of the robotic arm 30, for the tracking system 60to determine the position of the end effector 20 relative to thecoordinate system by encoder data. This tracking via encoders may, in anembodiment, be used as redundant tracking to ensure the accuracy of theoptical tracking described above.

The control system 610 can include a user interface 40. In anotherexample, the user interface 40 can be separate from the control system610 or can be communicatively coupled to the control system 610. Theuser interface 40 may include one or more of a monitor, a mouse, atouchscreen, and/or tablet or like handheld unit.

In some examples, the control system 610 can control aspects of thecutting system 100, based on a tracked position of the cutting element104 relative to a coordinate system. To determine position andorientation of the cutting element 104 during a surgical procedure, thetracking system 60 can be used in conjunction with the control system610 to control position, orientation and a cutting process. The controlsystem 610 may control the robotic arm 30 in its 3D working volume. Inan embodiment, the robotic arm 30 is a serial arm with the end effector20 movable in at least 6 degrees of freedom (DOF) relative to thesurgical table. This may include 3 rotational DOFs and 3 translationalDOFs. The control system 610 may therefore control the various joints tocontrol the position and/or orientation of the end effector 20 in thecoordinate system of surgery.

Another of the components that the control system 610 can control is theactuator 102 (FIG. 1 ). Based on signals received from the roboticcontroller 50, the cutting control mechanism 114 can cause the actuator102 (FIG. 1 ) to extend or retract at least one of the plurality ofcutting implements 108 into and out of the housing 106 (FIG. 1 ).

The control system 610 can also activate or deactivate at least one ofthe plurality of cutting implements 108 (FIG. 1 ) based on the trackedposition. In some examples, the control system 610 controls all of thecutting implements 108 (FIG. 1 ) together (e.g., at the same speed ordepth). In other examples, the control system 610 can control each ofthe plurality of cutting implements 108 independently, or certainfunctions of the cutting implements 108 (FIG. 1 ) can be controlledindependently. In other words, the rotational speed, retraction, orextension of each of the plurality of cutting implements 108 (FIG. 1 )can be separately controlled and adjusted.

The control system 610 can also control a rotational or oscillatingspeed of at least one of the cutting implements 108 (FIG. 1 ) based on atracked position. The control system 610 can control the rotational oroscillating speed of the plurality of cutting implements 108 (FIG. 1 )within the housing 106 (FIG. 1 ). In an example where the housing 106rotates or oscillates with the cutting implements 108, the controlsystem 610 can control a rotational or oscillating speed of the housing106 (FIG. 1 ).

In some examples, the control system 610 can be used to determine a zoneoccupied by the cutting element 104, such as using the position or theorientation of the cutting element 104, a target object, or a coordinatesystem. The zone can include a safety zone, an interaction zone, or afree-drive zone. In response to determining the zone is a free-drivezone, the control system 610 can permit interactive movement of the endeffector 20 and prevent autonomous movement of the end effector 20. Inresponse to determining the zone is an interactive zone, the controlsystem 610 can permit interactive movement and autonomous movement ofthe end effector 20.

The control system 610 can prevent movement (autonomous or interactive)into the safety zone. In an example, the control system 610 can, inresponse to determining that the zone is the interaction zone, causeautonomous movement of the end effector 20 to a cutting position. Theautonomous movement can be caused in response to selection of aselectable indication for the movement on the user interface 40. Theuser interface 40 can be used to select a predetermined cuttingposition, such as a position and/or orientation relative to the targetobject. In an example, the control system 610 can disable the selectableindication in response to determining the zone is a free-drive zone. Inan example, the control system 610 can activate the selectableindication in response to determining that the zone is the interactionzone.

After moving the end effector 20 to the cutting position, the cuttingelement 104 can be allowed to move interactively along a cuttingsurface. The cutting element 104 can be prevented from moving outside ofa cut plane or cut line by the control system 610. In an example, thecutting element 104 can be permitted to enter the safety zone by thecontrol system 610 while the cutting element 104 is in the cut plane orcut line. This permission can occur, in an example, only afterautonomous movement of the cutting element 104 to the cutting position.

In an example, the tracking system 60 can determine a trajectory of thecutting element 104, such as from an interactive force applied to thecutting element 104 or a portion of the cutting element 104, the endeffector 20, or the robotic arm 30. The control system 610 can determinethat the trajectory would cause the robotic arm 30 or a portion of therobotic arm, the end effector 20, or the cutting element 104 to enterthe safety zone. In response to determining that the trajectory wouldcause entry into the safety zone, the control system 610 can preventmovement of the robotic arm 30.

In an example, the control system 610 can establish the interaction zoneusing anatomical landmarks of the target object (e.g., a target bone) oridentified locations of the target object (e.g., digitized locations).The tracking system 60 can determine a position or an orientation of atarget object relative to the coordinate system. The position or theorientation of the cutting element 104 can be determined relative to theposition or the orientation of the target object by the tracking system60. In an example, the coordinate system is determined from the positionor the orientation of the target object. The activation and/ordeactivation of all or some of the cutting implements, along with othercontrol features such as the deceleration of the cutting implements, maybe performed by the control system 610 to avoid removing bone that it isdesired to preserve. Stated differently, some selective disabling ofcutting implements may be controlled to avoid certain bone, such as bonein a no-cut zone).

In some examples, the control system 610 can identify or determine if aportion of the bone to be removed was missed and to cause the cuttingsystem 100 to return to that portion and remove it.

FIG. 7 shows a flow chart illustrating a technique for preparing a bonesurface. The technique 700 can be used with the cutting systems 100,200, 300, 400, 500, 600, 900 and 1000 described in FIGS. 1-6 and 9-11 ,but can also be used with other cutting systems. Alternatively, thecutting systems 100, 200, 300, 400, 500, 600, 900 and 1000 can also beused with other techniques.

In technique 700, operation 702 can include to track, using a trackingsystem, movement of an end effector of a robotic arm. A cutting systemcan be coupled to the end effector, for example, as shown and describedin at least FIGS. 1-6 . The cutting system can include a housing and aplurality of cutting implements disposed in the housing. The housing canhave a superior surface and an inferior surface. The cutting implementscan be positioned in an (pattern (e.g., array) within the housing.Operation 702 may be performed continuously during technique 700 (eventhrough subsequent operations such as 704 and 706), or continuous duringgiven intervals in which the relative positioning is required. Operation702 may be performed in realtime.

In technique 700, operation 704 can include to determine, using thetracking system, a position of the end effector. Operation 704 may beperformed continuously during technique 700, or continuous during givenintervals in which the relative positioning is required. Operation 704,once have begun, may be performed simultaneously with operation 702.Operation 704 may be performed in realtime.

In technique 700, operation 706 can include to control, based on thedetermined position in operation 704, the movement of the plurality ofcutting implements. In the example where the plurality of cuttingimplements are cutting mills, each cutting mill can be rotated oroscillated, as well as the plurality of mills being rotated, oscillatedor translated together as one cutting element in a combined motion. Forexample, the operation 706 may be done at selected times while theoperations 702 and 704 are continuous.

In technique 700, operation 706 can include controlling the movement ofthe plurality of cutting implements to machine a planar surface on bonetissue. Suitable applications for machining a planar surface includeknee arthroplasties, including total knee arthroplasties.

Controlling the cutting system in operation 706 can include actuating,based on the determined position in operation 704, an actuator to extendand retract at least one of the plurality of cutting implements into andout of the superior surface of the housing, and/or translate the cuttingelements relative to a housing.

In technique 700, operation 706 can also include to activate ordeactivate, based on the determined position, at least one of theplurality of cutting implements. In some examples, all of the pluralityof cutting implements can be activated or deactivated together.

In technique 700, operation 706 can also include to move the cuttingimplements to produce the planar surface. In some examples, moving thecutting implements can include moving the housing together with orseparate from the cutting elements.

In some examples, moving the cutting implements can include acombination of movements. For example, operation 706 can includerotating, oscillating or translating each cutting implement. In someexamples, operation 706 can also include inducing a second motion to thearray of cutting implements to move the cutting elements together. Thissecond motion can be applied to just the plurality of cutting elements,or the second motion can be applied to the housing and the cuttingimplements together.

In other words, in the example of FIGS. 1-5 where the cutting implementsare shown as mills, in addition to each mill being rotated or oscillatedto perform the milling operation, a second motion can be provided tooscillate, rotate or translate the array of cutting implementscollectively. The combination of motions (e.g., compound motion) canfacilitate machining the bone tissue located in the gap(s) between thecutting implements.

In some examples, moving the cutting implements can include to adjust,based on the determined position, a rotation or oscillation speed of atleast one of the plurality of cutting implements. The rotation oroscillation speed of the plurality of cutting implements maybecontrolled and adjusted so that the speed of each cutting implement isthe same, or, the speed of individual cutting elements can beindividually controlled and adjusted. Individual adjustment can be usedto provide more customized machining. For example, if bone tissue acrossthe surface has different characteristics (density, brittleness,quality, etc.), the machine control can be adjusted locally at each ofthe plurality of cutting implements.

FIG. 8 illustrates a flowchart showing a technique for 800 performing asurgical procedure including controlling a cutting system in accordancewith some embodiments. As with technique 700, the technique 800 can alsobe used with the cutting systems 100, 200, 300, 400, 500, 600, 900 and1000 described herein, but can also be used with other cutting systems.Alternatively, the cutting systems 100, 200, 300, 400, 500, 600, 900 and1000 described herein can also be used with other methods.

The control system (e.g. 610, FIG. 6 ) can be adapted to determine a cutzone and a no-cut zone. Using the determined cut zones, the controlsystem can control position, orientation and a cutting process of thecutting tool to permit cutting in the cut zone and to prevent cutting inthe no-cut zone.

The control system can determine and establish the cut zone usinganatomical landmarks of a target bone. In some examples, the cuttingelement can be allowed to enter a safety zone while in the cut plane.

The technique 800 can include an operation 802 to track a cutting systemaffixed to an end effector of a robotic arm. The cutting system caninclude a plurality of cutting implements disposed in a housing.Operation 802 may be performed continuously during technique 800 (eventhrough subsequent operations such as 804), or continuous during givenintervals in which the relative positioning is required. Operation 802may be performed in realtime.

The technique 800 can include a decision operation 804 to perform a zonedetermination. In an example, the decision operation 804 can beperformed using a tracking system. For example, a tracking system can beused to track an end effector of a robotic cutting system (e.g., using arobotic controller) and a position or positions of a bone or otherpatient anatomy (e.g., using an optical tracker). The tracking systemcan determine where the end effector is relative to aspects of patientanatomy or absolute positions of either or both the end effector and thepatient anatomy. When the determination indicates the zone is a safetyzone 806, the technique 800 can include an operation 807 to allowautonomous movement only. For example, the robotic arm can resist anymovement other than autonomous movement controlled by a roboticcontroller. An intentional or accidental force, such as by a surgeon,can be resisted or prevented by the robotic arm (e.g., using a counterforce initiated by a robotic controller or by simply not enablingmovement of any robotic joints). In certain examples, the robotic armcan only be moved through commanded movements. In these examples, thecommanded movements can be autonomous or interactive. Within the safetyzone the controller can limit commanded movements to only includeautonomous movements.

When the determination indicates that the zone is a free drive zone 808,the technique 800 can include an operation 809 to allow interactivemovement only (e.g., prevent the robotic arm from moving autonomously orshutting off power or control to the robotic arm). In an example,interactive movement can include force applied by the robotic arm, forexample in response to an external force (e.g., by a surgeon) on thearm, as a force assist, but cannot include autonomous (e.g., without theexternal force) movement.

When the determination indicates the zone is an interaction zone 810,the technique 800 can include an operation 812 to allow autonomousmovement or interactive movement. For example, when an end effector at adistal end portion of a robotic arm is in the interaction zone 810,movement can be controlled by a robotic controller or a surgeonmanipulating the robotic arm.

The technique 800 can include an operation 814 to autonomously move theend effector such that a plurality of implements can be rotated,oscillated or translated to prepare a planar bone surface. Operation 814can be performed in response to determining that the cutting element hasbeen moved into the interaction zone. In an example, the interactionzone can be a zone where the surgical instrument can perform a machiningstep, such as a bone preparation step in a knee arthroplasty. Thetechnique 800 can include an operation 816 to determine that the bonepreparation step has been completed.

The technique 800 can include an operation 818 to autonomously move theend effector. In an example, the technique 800 may include determiningthat a bone surface preparation has been completed, and moving the endeffector to the free drive zone 808 or the interaction zone 810. In anexample, operations 814, 816, and 818 can be initiated only when therobot is within the interaction zone 810, but can actually take placewithin the safety zone 806.

The end effector can be autonomously moved (e.g., by the robotic armcontrolled by a robotic controller), for example in response todetermining that the bone preparation has been completed. The roboticarm may also have a collaborative mode in which a human operator maydisplace the robotic arm. The collaborative mode may be for non-preciselarge range maneuvers, such as moving the robotic arm away from theoperation site upon completion of the surgery.

FIG. 9A illustrates a perspective view of another example cutting system900 having cutting implements 908 that can be used with the surgicalrobot 10 of FIG. 1 , in accordance with at least one example. FIG. 9Billustrates a perspective view of the cutting system 900 of FIG. 9A witha housing 906 shown in FIG. 9A removed.

In general, like the cutting system of FIGS. 1-5 , the cutting system ofFIGS. 9-11 can be used to prepare a planar bone surface, and can employthe features described with respect to FIGS. 1-8 .

The cutting system 900 can include a cutting element 904 having atwo-dimensional cutting surface including a cutting band 930 (e.g., aflexible cylindrical cutting band).

Like the example of FIG. 1 , the cutting system 900 can include an endeffector connection mechanism 916 adapted to couple the cutting system900 to an end effector of a robotic arm (e.g., 30, FIG. 1 ). Themechanism 916 is shown oriented in a direction that is transverse to theplane of the cutting band 930. It is however considered to orient themechanism 916 in a parallel or quasi parallel manner relative to theplane of the cutting band 930 (e.g., from −20 degrees to 20 degrees froma parallel relation).

The cutting system 900 can also include a first cylindrical drive member932 disposed along a first edge 936 (e.g., side) of the housing 906, anda second cylindrical drive member 934 disposed along a second edge 938(e.g., side) of the housing 906. The cutting band 930 can extend (e.g.,be stretched) between the first cylindrical drive member 932 and thesecond cylindrical drive member 934. The cutting band 930 can form aclosed loop (e.g., a flexible eternal band). The cutting band 930 can berotated upon activation of the cutting element 904 by a rotator (e.g., amotor). In some examples, the rotators can reside inside of the firstand/or second cylindrical drive members 932, 934. In some examples,instead of rotating or in addition to rotating the cutting band, thecutting band can be oscillated upon activation of the cutting element904 by an oscillator (e.g., FIG. 1, 110 ). The cutting band 930 may alsobe rotated by way of a transmission. Examples of transmissions includetendons and pulleys, chains and sprockets, gear drives, etc. It iscontemplated to use endless worms, etc, for the drive to come from alateral axis, for instance when the mechanism 916 is in the parallel orquasi parallel arrangement described above.

As shown in FIGS. 9A and 9B, the cutting band 930 can include abrasiveelements 908. In some examples, the abrasive elements 908 can be adheredto or molded into the cutting band 930.

FIG. 10 illustrates a perspective view of a portion of the cuttingsystem 900 of FIG. 9 showing another example cutting band 1030, inaccordance with at least one example. The cutting band 1030 can beformed from a plurality of cutting implements 1008 joined together as anunending band. Each of the plurality of cutting implements 1008 can beformed as an elongate or linear cutting implement. The plurality ofcutting implements 1008 can be joined to each other or to a band ofmaterial to form the cutting band 1030. In some examples, the pluralityof cutting implements 1008 can be joined to each other by interlockinggeometric formations or coupling elements incorporated into the cuttingimplements 1008. The cutting implements 1080 can be coupled to eachother in a flexible manner so the plurality of cutting implements 1008can bend relative to one another.

FIG. 11 illustrates a perspective view of three example geometries ofcutting implements 1108A, 1108B, 1108C that can be used in the cuttingsystem 1000 of FIG. 10 , in accordance with at least one example.

In an example, the term “machine readable medium” can include a singlemedium or multiple media (e.g., a centralized or distributed database,or associated caches and servers) configured to store one or moreinstructions. The term “machine readable medium” can include any mediumthat is capable of storing, encoding, or carrying instructions forexecution by a machine and that cause the machine to perform any one ormore of the techniques of the present disclosure, or that is capable ofstoring, encoding or carrying data structures used by or associated withsuch instructions. Non-limiting machine readable medium examples caninclude solid-state memories, and optical and magnetic media. Specificexamples of machine readable media can include: non-volatile memory,such as semiconductor memory devices (e.g., Electrically ProgrammableRead-Only Memory (EPROM), Electrically Erasable Programmable Read-OnlyMemory (EEPROM)) and flash memory devices; magnetic disks, such asinternal hard disks and removable disks; magneto-optical disks; andCD-ROM and DVD-ROM disks.

Various Notes & Examples

Each of these non-limiting examples can stand on its own, or can becombined in various permutations or combinations with one or more of theother examples.

Example 1 is a robotically controlled planar cutting system, the planarcutting system comprising: a housing including a superior surface and aninferior surface; a cutting element disposed within the housing, whereinthe cutting element is exposable through the superior surface and ispopulated with a plurality of cutting implements that are arranged tomachine a planar surface; a cutting control mechanism in communicationwith a robotic controller to control the operation of the cuttingelement to machine the planar surface.

In Example 2, the subject matter of Example 1 includes, wherein thecutting control mechanism receives signals from the robotic controllerto expose the two-dimensional cutting surface outside the housing.

In Example 3, the subject matter of Examples 1-2 includes, wherein thecutting control mechanism activates or deactivates the cutting elementbased on signals from the robotic controller.

In Example 4, the subject matter of Examples 1-3 includes, and endeffector connection mechanism to couple the housing to a robotic arm.

In Example 5, the subject matter of Examples 1-4 includes, an oscillatoroperably coupled to at least one of the cutting element and the housingto oscillate at least one of the cutting element and the housing.

In Example 6, the subject matter of Examples 1-5 includes, a rotatoroperably coupled to at least one of the cutting element and the housingto rotate at least one of the cutting element and the housing.

In Example 7, the subject matter of Examples 1-6 includes, wherein thetwo-dimensional cutting surface includes a plurality of cutting millsdisposed in a pattern.

In Example 8, the subject matter of Examples 1-7 includes, wherein thecutting control mechanism receives signals from the robotic controllerto expose the two-dimensional cutting surface outside the housing.

In Example 9, the subject matter of Example 8 includes, wherein thesystem includes a mechanism to oscillate or rotate the array of cuttingmills.

In Example 10, the subject matter of Examples 8-9 includes, wherein eachcutting mill of the plurality of cutting mills rotates upon activationof the cutting element.

In Example 11, the subject matter of Examples 8-10 includes, whereineach cutting mill of the plurality of cutting mills oscillates uponactivation of the cutting element.

In Example 12, the subject matter of Examples 1-11 includes, wherein thetwo-dimensional cutting surface includes a flexible cylindrical cuttingband.

In Example 13, the subject matter of Example 12 includes, wherein thecutting control mechanism receives signals from the robotic controllerto expose the two-dimensional cutting surface outside the housing.

In Example 14, the subject matter of Examples 12-13 includes, whereinthe cutting element includes a first cylindrical drive member disposedalong a first edge of the housing and a second cylindrical drive memberdisposed along a second edge of the housing opposite the first edge.

In Example 15, the subject matter of Example 14 includes, wherein theflexible cylindrical cutting band is stretched between the firstcylindrical drive member and the second cylindrical drive member.

In Example 16, the subject matter of Example 15 includes, wherein theflexible cylindrical cutting band rotates upon activation of the cuttingelement.

In Example 17, the subject matter of Examples 15-16 includes, whereinthe flexible cylindrical cutting band oscillates upon activation of thecutting element.

Example 18 is a robotically controlled planar cutting system, the planarcutting system comprising: a housing including a superior surface and aninferior surface; a cutting element having a plurality of cuttingimplements disposed in the housing, wherein the plurality of cuttingimplements are arranged in an array; an end effector connectionmechanism to couple the housing to a robotic arm; and a cutting controlmechanism in communication with a robotic controller to control theoperation of the cutting implements to machine a planar surface.

In Example 19, the subject matter of Example 18 includes, wherein theplurality of cutting implements are arranged and controlled tocooperate, such that together the plurality of cutting implementsmachine the planar surface.

In Example 20, the subject matter of Examples 18-19 includes, whereinthe plurality of cutting implements includes at least three cuttingmills positioned in a triangular arrangement such that lines tangent toouter radii of the at least three cutting mills form a triangle.

In Example 21, the subject matter of Examples 18-20 includes, whereinthe plurality of cutting implements includes at least four cutting millspositioned in a parallelogram arrangement such that lines tangent toouter radii of the at least four cutting mills form a parallelogram.

In Example 22, the subject matter of Examples 18-21 includes, whereinthe plurality of cutting implements are positioned in a trapezoidalarrangement such that lines tangent to outer radii of the plurality ofcutting mills form a trapezoid.

In Example 23, the subject matter of Examples 18-22 includes, whereinthe plurality of cutting implements includes a first cutting implement,a second cutting implement and a third cutting implement, and wherein anaxis extending tangent from the first cutting implement to the thirdcutting implement intersects a portion of the second cutting implement.

In Example 24, the subject matter of Examples 18-23 includes, whereinthe plurality of cutting implements includes a first cutting implement,a second cutting implement and a third cutting implement, and wherein anaxis extends tangent to the first cutting element, the second cuttingelement and the third cutting implement.

In Example 25, the subject matter of Examples 18-24 includes, wherein aperimeter of a distal end portion of the housing includes a shieldaround the plurality of cutting implements to protect soft tissueadjacent to a bone cutting site.

In Example 26, the subject matter of Examples 18-25 includes, whereinthe housing includes a generally trapezoidal perimeter around theplurality of cutting implements to protect soft tissue surrounding abone cutting site.

In Example 27, the subject matter of Examples 18-26 includes, anactuator to move at least one of the plurality of cutting implementsrelative to the housing to retract or extend the at least one cuttingimplement thereby preventing or enabling a cutting operation to beperformed.

In Example 28, the subject matter of Examples 18-27 includes, anoscillator to oscillate at least one of the plurality of cuttingimplements and the housing.

In Example 29, the subject matter of Examples 18-28 includes, a rotatorto rotate at least one of the plurality of cutting implements.

In Example 30, the subject matter of Examples 18-29 includes, a trackingsystem to determine a position and an orientation of the cutting elementrelative to a coordinate system; and a control system to controlposition, orientation and a cutting process of the cutting tool.

In Example 31, the subject matter of Example 30 includes, wherein thecontrol system controls an actuator to extend and retract at least oneof the plurality of cutting implements into and out of the housing basedon a tracked position.

In Example 32, the subject matter of Examples 30-31 includes, whereinthe control system activates or deactivates at least one of the cuttingimplements based on a tracked position.

In Example 33, the subject matter of Examples 30-32 includes, whereinthe control system controls a rotational or oscillating speed of atleast one of the cutting implements based on a tracked position.

In Example 34, the subject matter of Examples 30-33 includes, whereinthe control system is adapted to: determine a cut zone; determine ano-cut zone; and control position, orientation and a cutting process ofthe cutting tool to permit cutting in the cut zone and to preventcutting in the no-cut zone.

In Example 35, the subject matter of Example 34 includes, wherein thecontrol system is configured to establish the cut zone using anatomicallandmarks of a target bone.

In Example 36, the subject matter of Examples 34-35 includes, whereinthe cutting element is allowed to enter a safety zone while in the cutplane.

Example 37 is a method for operating a surgical robot, the methodcomprising: tracking, using a tracking system, movement of an endeffector of a robotic arm having a cutting system including a pluralityof cutting implements disposed in a housing, wherein the housing has asuperior surface and an inferior surface, and wherein the plurality ofcutting implements are arranged in an array; determining, using thetracking system, a position of the end effector; and controlling, basedon the determined position, movement of the plurality of cuttingimplements to machine a planar surface.

In Example 38, the subject matter of Example 37 includes, wherein theplurality of cutting implements are arranged in an array.

In Example 39, the subject matter of Examples 37-38 includes, actuating,based on the determined position, an actuator to extend and retract atleast one of the plurality of cutting implements into and out of thesuperior surface of the housing.

In Example 40, the subject matter of Examples 37-39 includes, moving theplurality of cutting implements to remove bone tissue in between theplurality of cutting implements.

In Example 41, the subject matter of Examples 37-40 includes, adjusting,based on the determined position, a rotation or oscillation speed of atleast one of the plurality of cutting implements.

Example 42 is at least one non-transitory machine-readable mediumincluding instructions for operation of a robotically controlledsurgical planar cutting system, and the instructions, when executed by aprocessor, cause the processor to perform operations to: track movementof an end effector of a robotic arm, using a tracking system, therobotic arm having a cutting system attached to the end effector, thecutting system including a plurality of cutting implements disposed in ahousing, wherein the housing has a superior surface and an inferiorsurface, and wherein the plurality of cutting implements are arranged inan array; determine a position of the end effector using the trackingsystem; and control movement of the plurality of cutting implements tomachine a planar surface, based on the determined position.

In Example 43, the subject matter of Example 42 includes, to controlmovement of the plurality of cutting implements includes to controlmovement of the plurality of cutting implements arranged in an array.

In Example 44, the subject matter of Examples 42-43 includes, toactuate, an actuator to extend and retract at least one of the pluralityof cutting implements into and out of the superior surface of thehousing, based on the determined position.

In Example 45, the subject matter of Examples 42-44 includes, to movethe plurality of cutting implements to remove bone tissue in between theplurality of cutting implements.

In Example 46, the subject matter of Examples 42-45 includes, to adjusta rotation or oscillation speed of at least one of the plurality ofcutting implements based on the determined position.

Example 47 is at least one machine-readable medium includinginstructions that, when executed by processing circuitry, cause theprocessing circuitry to perform operations to implement of any ofExamples 1-46.

Example 48 is an apparatus comprising means to implement of any ofExamples 1-46.

Example 49 is a system to implement of any of Examples 1-46.

Example 50 is a method to implement of any of Examples 1-46.

The invention claimed is:
 1. A system comprising: at least oneprocessor; a non-transitory machine-readable medium includinginstructions for operation of a robotically controlled surgical planarcutting system, and the instructions, when executed by a processor,cause the processor to perform operations to: track movement of an endeffector of a robotic arm, using a tracking system, the robotic armhaving a cutting system attached to the end effector, the cutting systemincluding a plurality of cutting implements disposed in a housing,wherein the housing has a superior surface and an inferior surface, andwherein the plurality of cutting implements are arranged in an array;determine a position of the end effector using the tracking system; andcontrol movement of the plurality of cutting implements to machine aplanar surface, based on the determined position.
 2. The systemaccording to claim 1, wherein to control movement of the plurality ofcutting implements includes to control movement of the plurality ofcutting implements arranged in an array.
 3. The system according toclaim 1, including to actuate, an actuator to extend and retract atleast one of the plurality of cutting implements into and out of thesuperior surface of the housing, based on the determined position. 4.The system according to claim 3, wherein to actuate, an actuator toextend and retract at least one of the plurality of cutting implementsinto and out of the superior surface of the housing includes to displacethe at least one cutting implement relative to the housing in adirection parallel to the planar surface.
 5. The system according toclaim 1, further including to move the plurality of cutting implementsto remove bone tissue in between the plurality of cutting implements. 6.The system according to claim 1, further including to adjust a rotationor oscillation speed of at least one of the plurality of cuttingimplements based on the determined position.
 7. The system according toclaim 1, further including the robotic arm having the cutting systemattached to the end effector, the cutting system including the pluralityof cutting implements disposed in the housing, the plurality of cuttingimplements being arranged in the array.
 8. The system according to claim7, wherein the cutting implements are cutting mills.
 9. The systemaccording to claim 8, wherein axes of rotation of the cutting mills areparallel to one another.
 10. The system according to claim 7, whereinthe robotic arm includes a transmission for the cutting implementshaving a shaft extending in a direction parallel or quasi-parallel tothe planar surface.
 11. The system according to claim 7, furtherincluding a shield projecting from the superior surface, the shieldhaving a patient-specific contour being a negative of a patient's bonesurface.
 12. The system according to claim 7, further including at leastone clamp adapted to fix the housing to a bone.
 13. The system accordingto claim 1, further including the tracking system.